Two-Spotted Mite

Scientific Name: Tetranychus urticae

Description Of Adults: Adults are usually less than 0.5 mm long with eight legs, and their spider‐like appearance can only just be seen with the naked eye. Under a x10 hand lens, the active form appears translucent or sometimes greenish with two conspicuous black spots on the body.

Immature Stages: The clear, spherical egg is followed by three immature stages that are similar to the adult stage. All stages of the life cycle occur together, mostly near the veins of the underside of leaves.

The mite spends winters either as an orange, inactive, fertilised female in debris or as the active two-spotted form, breeding on other leafy hosts. The life cycle can be completed in 1‐4 weeks, depending on temperature, and there are many overlapping generations each year. Populations increase rapidly in hot dry weather.

Damage is minor and infrequent. The appearance of mites is often an indication of excessive insecticide use. Insecticide kills the biological control agents, such as predatory lady beetles and mites.

When mites feed, they suck the contents out of individual plant cells. The feeding can cause extensive leaf, flower and fruit damage. Leaf damage is distinguished by the development of yellow mottled or stippled areas, particularly on the underside of leaves. Damage first appears near the main leaf veins. In some strawberry varieties, the feeding of two‐spotted mites can result in reddening of the leaves.